Another volunteer on Des Moines’ south side stood on a home’s stoop, knocking on a door that remained unopened. So he shouted through the door.

“I’m here representing Senator Bernie Sanders ...

“Hello? ... Hello?"

“People want to be asked for their vote. When people hear from neighbors, somebody they know or a volunteer who speaks from the heart, that’s most important.”

Jordan Russell, a spokesman for Sen. Marco Rubio in Iowa

He tromped through the snowy yard to the next house.

The 11 Republicans and three Democrats campaigning in Iowa are pulling out all the stops — and aren't stopped by being ignored.

The campaign for Republican Rand Paul has made 800,000 calls and is shooting for a million — and, yes, cellphone numbers can be found by crafty campaign staff. Republican Jeb Bush’s campaign has promised a chance at a dinner with the Republican if you can lure six people to the caucus, “No purchase necessary.”

Sixty people are canvassing for Republican Carly Fiorina, and other supporters are showing a screening of a documentary about her in their homes. Republican Donald Trump’s campaign is firing out emails asking for people to make calls: “You don’t have to bring anything at all — and we’ll provide you with food and beverages. We’ll even have contests and special prizes for our top performers.”

The campaigns are promising rides to the caucuses, luring celebrities to Iowa, such as Jamie Lee Curtis for Democrat Hillary Clinton. They are employing family surrogates, such as Democrat Martin O’Malley’s three adult children.

But the best method may be the most old-fashioned: Neighbors and fellow Iowans knock on your door for a little face-to-face convincing.

“Research has shown that direct, personal contact works better than campaign brochures and the like, and face-to-face contact, particularly from friends and relatives, works best,” said Dennis Goldford, professor of political science at Drake University.

'I think they like the attention'

Freddy Chavez, representing Sanders' campaign, had knocked on about a half-dozen doors last Sunday on the south side. He came to Iowa from his home in Berkeley, Calif., not as a neighbor but as a volunteer with a pedigree. He’s the nephew of famous farm labor activist Cesar Chavez.

Most people didn’t answer the door so he resorted to shouting his mission from outside in English and Spanish. The campaign had targeted this heavily Latino neighborhood, but on any block, Iowans aren’t used to people knocking, as in the days of vacuum cleaner salesmen.

“Research has shown that direct, personal contact works better than campaign brochures and the like, and face-to-face contact, particularly from friends and relatives, works best.”

Dennis Goldford, professor of political science at Drake University

Chavez is asked what these pleas in the last week can do after Iowans have been bombarded with advertisements, media reports and politicians for more than 18 months.

“Here in Iowa people wait until the last minute to decide,” he said, before smiling. “I think they like the attention.”

Joining him was Michael Vega, 21, of Des Moines, who is paid by the campaign. He wanted to learn from Chavez, who marched with his uncle. And Vega wanted to spread a message about income inequality.

Vega said he’s seen his family struggle to get by because of discrimination and low pay. “My mom works in fast food, and my dad works in a factory.”

Chavez said he came from a tradition of revolution among ancestors fighting income disparity in Mexico early in the last century. He said Latinos connect with Sanders’ call to “Join the Revolution.”

After several door knocks, Chavez and Vega caught two men in a garage fixing a pickup. Only one spoke English.

David Allison, 30, crawled out from under the truck and assured Chavez that he is voting for Sanders but didn’t know about the caucus or where it was. Chavez told him that he might not be able to vote for Sanders in the general election if he doesn’t go to caucus, because Sanders needs to win the Democratic party's nomination first.

Allison may have been uneducated about the caucus, but he knew the issues. He got into a nuanced discussion with Chavez about the minimum wage, taxes and health care.

Chavez may have talked him into attending after all.

“All the eyes of the nation are here now,” Chavez told him before going to the next house.

Just don't call us at dinner

For months, Iowans have been hearing the term “ground game.” It’s a football analogy. No fancy-pants forward passes to quickly move down the field will win it here. Just a grind-it-out, one-on-one blocking approach to move the ball 2 yards at a time.

And that’s what happens at the call center for Rubio. One call at a time.

“People want to be asked for their vote,” said Jordan Russell, a spokesman for Rubio in Iowa. “When people hear from neighbors, somebody they know or a volunteer who speaks from the heart, that’s most important.”

Mostly young adults line long tables with call lists and phones. Under the table is indoor-outdoor carpet with white lines like a football field. The walls are plastered with cut-out paper footballs positioned on a paper field. The balls carrying the names of the top call performers have advanced farthest up the field.

Volunteer Alex Richmond, 25, moved here from Michigan 18 months ago to work on Rubio’s campaign and said he has found Iowans polite, except when he interrupts their dinner.

One of the elder statesman volunteers is Dixie Watters, who is in her 50s and lives just outside of Des Moines. She claims to have made 1,500 calls.

“I just turned one (to Rubio) tonight,” she said. “She was undecided.”

Move that woman’s football.

Political experts have told The Des Moines Register that the Democrats won’t match the record 2008 turnout of 240,000 spurred by the field of Barack Obama, Hillary Clinton and other party luminaries. With the Republicans' large field, they could do better than the record 121,500 that went to caucus in 2012.

Typically, less than 20% of registered voters turn out for the caucuses. That makes the final push vital to the campaigns.

Passion keeps volunteers going

Behind the hard-nosed campaign strategies are often volunteers that have given up time because they believe in the cause.

Only five days after their fellow campaign volunteer and friend Braden Joplin, 25, died in a car crash in western Iowa, Californians Ryan Shellooe, 23, and Aaron Ohnemus, 18, were back making calls in Republican candidate Ben Carson’s Urbandale office.